Switching apparatus with periodically operated contacts



Oct. 28, 1947. c. ZELLWEGER Er AL 2,429,659

SWITCHING APPARATUS WI TH PERIODICALLY OPERATED CONTACTS F11 ma a, 1942 INVENTORS CARL Zsuwzazn Patented Oct. 28, 1947 SWITCHING APPARATUS'WITH PERIOD] CALLY'OPERATED CONTACTS.

Carl Zellwegenlurich, andfI-Ians. Hugo Durheim.. Berne, Switzerland assignors. to. International Standard Electric Corporation,

New. York,

N;. Y.,. a corporation. of Delaware.-

Application May 8, 1942, Serial No. 442,273 In Switzerland June-6, 1941' I 10 Claims. 1

This invention relates to a switching apparatus with periodically actuated contacts-such as used. for example in contacting converters. for. converting alternating current into direct current or direct current into alternating current.

A particular object of the: present invention: isv to provide an improved switching apparatus; employing an advantageous typeof rolling andpressure engagement ofthe contact members and improved controlling or actuating means for: a rolling type of. movable contact designed to operate with a maximum or accelerated speed during the, changeover intervalas is desiredto effect. a sparkless change-over switching engagement and to adapt the change-over period as much as. possibletotheshort, time interval during which the current passes throughzero; A. further, ob.- jectis to. produce an actuating means which in its. operation: will. substantially eliminate; the objectionable vibrations common: tomany types of converter switching mechanisms as at: present employed.

The switching apparatus accordingstothepresent invention. is characterised by at least one rolling contact which is periodically moved to: and

fro. I

The. invention will now be described: in connec-- tion. with some embodiments whichare schematis cally. represented in the accompanying drawing; In thisdrawing only such partsare'shown which are necessary for the understanding: of: the invention, and similar parts are designated: by equal;

reference numerals.

In the. drawing- Fig. 1 shows partly in section aside View of. a: first embodiment. for use, in a triphase contacting converter,.

Fig. 2. is a front View of an arrangement ofv the stationary contact members providing Sta-- tionary feeding. to: the movable contact member of a phase, the said arrangement being used in:

the contact devices of the switching apparatus-- according toFig. 1,

Fig. 3' shows a second embodiment in which the;

driving mechanisms for the contact devices do not comprise springs, and

Figs 4 and 5 are views in front and side. elevation showing a modified driving mechanism; for operating one. phase of a third embodiment of the invention.

The switching apparatus of Fig. 1. comprises one contact device for each phase of the triphasecurrent, said-contact device having two stationary contact members I and 2 and a stationary feeder contact member 3 as shown in Fig. 2. The con tjactmembers l-, 2 and, 3 are mounted on aplate 5 of insulating material, the spaces between said contact" members being at least partly filled with insulating material upto the heightof the contact faces to provide an almost uninterrupted rolling surface for the-rolling. contact. Thecontact. members are provided with connecting terminals (not shown) for the connecting lead. The-p1ate5 and the-contact members I, 2- and: 3 may be designed in such a way that they can be. easily replaced. The plate 5; and the contact members I; and 2 may be provided with corresponding means for changing the; relative. position of, the contacts with; respect. to one another and the; co-opera-ting rolling; contact; i; e.. the movable. cont-act member; 4;, whereby the COD-'1'- tact device may be adjusted with respect to the zero; point of the current of this, phase and the changeover time.

The; plate 5 is mounted on a, contact support? 6, preferably of high quality light metal. and sliding in: slide grooves of the fixed part 1. A pressure spring 8 resting on, one side on the adjusting plate 9' presses against the contact support 6. The pressure spring 8;. the stress. upon Which. remains constant afterv the adjustment. of the. pressure,,servesito-provide the desired contact pressure between the contacts: I, 2' and 3 on the one hand and the rolling contact 4 on the other. hand by: pressing the contacts mounted on the contact support 6 against the rolling contact 4.. This. spring may be tensionedmore or less by means of the, adjusting screw I I screwed. into the fixed par-t Hl, whereby the contact pressureis changed, The screw l I is secured by meansof the; nut,- I Z. The parts I and H]. may form part of. the casing. ofthe switching apparatus; part It may belong, to; a cover which may be fixed tov the part 1 of the casing by means of screws. or latches. With such a construction the stationary contact members of, the contact device may be easily adjusted or removed, for: instance, for maintenance purposes,

The. movable contact member 4 is: mounted on an insulating piece, t4 and is of a. form and of dimensions whereby its peripheral contact surface has an engaging area coextensive with and conforming to, the surfaces of the stationary members 1, Z, 3, and 5 engaged thereby. This. insulating piece in turn is-mounted' on a flange l3 of the sector-shaped control member 15. The latter is pivoted on the pivot I'G of the slide H, said pivot supporting also an idler wheel -l-8 pressed against. the cam disc 20 of this phase by means of pressurespring 1:9. The, slide H is:

slideably mounted on two guiding rods 2I screwed into the fixed part 22, which may form part of the casing of the switching apparatus, and secured by nuts 23. The three cam discs 20, 20 and 22" of the three phases are mounted on the common driving shaft 24 driven by a synchronous motor (not shown) and are shifted from one another by 120.

The switching apparatus according to Fig. 1 operates as follows:

Upon rotation of the cam disc 28 in the direction of the arrow to the position shown in dotted lines, the idler 58, due to the action of spring I9 pressing on the slide I'I, follows the cam disc, so that the rolling contact 4 rolls over contact 2, the insulating portion between the contacts I and 2 and the feeder 3 until the control member I5 finally reaches the position indicated by dotted lines. It will be evident, that, since the control member forms part of a rolling wheel, so that the distance between the contacting point and the plane determined by the axis of the driving shaft and the idler does not change, the contact pressure determined by the pressure spring 8 will be the same in ail positions of the control member, so that chattering cannot occur. Upon further rotation of the cam disc 20 the control member I5 starts to return, the cam disc pressing the idler I8 downwards against the pressure of spring I9.

It will be evident, that the speed increases from zero at the beginning of the movement of the control member in one direction and from zero at the beginning of the movement in the other direction to a maximum value at about midway, so that the speed of the rolling contact is greatest when it passes from contact 2 to contact I or from contact I to contact 2, i. e. during the change-over period. Thereby the changeover time is substantially reduced as compared with switching apparatus with continuously rolling contacts and the change-over is improved. The cam discs do not need to be circular but may be adapted to the requirements of the desired change-over speed.

The switching apparatus according to Fig. 3 comprises for each phase two oo-operating cam discs 25 and E5 of equal size, which are mounted on the shafts 2i and 28 respectively and which always have the same angular position. Each cam disc is provided at its periphery with a ball race 29, Between the ball races 29, 3D is arranged an idler is pivoted on the pivot 3| of the control member I5 the axis of the shafts 27 and 28 and the idler l8 being in the same plan. The cam discs with the ball races and the idler are so dimensioned and the shafts 21, 28 are so spaced, that the ball races 29, 3G and the idler i8 are permanently in touch with one another. The idler I8 may also be provided with a ball bearing or the like and is pressed against the guide rail -32 by means of the contact pressure spring 8 (shown in Fig. l) which exerts pressure upon the stationary contact members via the control member I5. The guide rail 32 may form part of the casing or may be mounted thereon and may be provided with a groove in which the idler is rolling, so that a displacement in the direction of the axis of the driving shafts 21, 28 is prevented. The contact device may be exactly similar to that shown in Fig. l.

The two shafts 2?, 23 are driven by a motor (not shown) on the shaft of which a toothed wheel 33 is mounted which is in engagement with two toothed wheels 3%, 35 of equal size mounted on the shafts 27, 28. Thus said shafts rotate in the same sense and with the same speed. Of course another ratio could be used, if desired, between the toothed wheel 33 on the one hand and the toothed wheels 34, 35 on the other hand. The cam discs of the driving mechanisms for the other two contact devices of the contacting converter are mounted on the same shafts 21, 2B and are displaced from one another and against the shown cam discs by These driving mechanisms are exactly similar to that shown.

The switching device of Fig. 3 operates as follows:

If the two gear wheels 34, 35 are rotated clockwise by the synchronous motor the ball race 30 of cam disc 26 pushes the idler I8 upwards whilst the cam disc 25 retracts. Thereby the movable contact member mounted on the control member is rolled on the stationary contact members until the two cam discs have reached their uppermost position which is shown in dotted lines, whereupon the idler l8 is again pushed downwards by the cam disc 25, whilst the cam disc 25 retracts.

The switching apparatus of Figs. 4 and 5 comprises as a driving mechanism for each phase but one single cam disc 3! which is mounted on the common driving shaft 4I together with the not shown cam discs for the other phases. The cam disc 3'! which is recessed at its periphery is provided with a ball race 38 which together with the recessed portion of the disc form a guiding groove 39 as it is evident from Fig. 4. In the guiding groove rolls a guide roller 40 pivoted on the pivot I4 of the control member I5, the other end of the pivot supporting an idler I 8 which rolls on the guide rail 32. The latter may also be provided with a groove to prevent lateral displacement and may form part of the casing or may be fixed thereto. The three cam discs are shifted against one another by 120.

The contact device which is not shown may be similar to that of Fig. 1.

As it will be evident from the Figs. 3, 4 and 5 the driving mechanisms of the two switching apparatus shown in these figures do not possess restoring springs nor sliding parts but only rolling parts so that the driving power required will be small. Due to the lack of restoring springs and of sliding parts the stress and consequently wear of the elements will be small, and vibration reduced and in consequence greater reliability in operation is obtained.

What is claimed is:

1. Switching apparatus of the character de scribed comprising a stationary multiple contact member and a movable contact member provided with a curved contact adapted for rolling engagement with the stationary contact member, actuating means for the movable contact member with constant engagement with one of the contacts thereof adapted to impart a to and fro rolling movement thereto, said actuating means including a rotary shaft, an excentric thereon and said shaft being positioned substantially in alignment with the axis of rotation of the movable contact member.

2. Switching apparatus of the character described comprising a stationary multiple contact member and a movable contact member adapted for rolling contact engagement with the stationary contact member with constant engagement with one of the contacts thereof, said movable member being provided with a pivotal connection supported for reciprocal movement in a substantially rectilinear path, an operating shaft positioned substantially in alignment with said path and an eccentric carried by the shaft arranged to efiect movement of the pivotal connection thereby to have accelerated motion at the intermediate portion of each stroke thereof.

3. Switching apparatus of the character described comprising a stationary contact member having two longitudinally separated and insulated contacts and a third elongated insulated contact coextensive with the first contacts, a movable contact member provided with a curved surface contact and having rolling contact engagement with the stationary contacts and means to impart a to and fro rolling movement to the movable contact member in a direction parallel to the elongated contact.

4. Switching apparatus of the character described comprising a stationary contact member, a movable contact member provided with a curved surface contact for rolling contact engagement with the stationary contact, a controlling member pivotally connected to the movable contact member at the axis of rotation thereof and actuating means for reciprocating the control member to effect rolling movement of the movable contact member.

5. Switching apparatus of the character described comprising a stationary contact member, a movable contact member provided with a curved surface contact for rolling contact engagement with the stationary contact, a controlling member pivotally connected to the movable contact member at the axis of rotation thereof and actuating means for reciprocating the control member to effect rolling movement of the movable contact member, and one of said contact members being resiliently supported to effect pressure engagement between the contact surfaces.

6. Switching apparatus of the character described comprising a stationary contact member, a movable contact member provided with a curved surface contact for rolling contact engagement with the stationary contact, a controlling member supported for movement in a plane coinciding with the axis of rotation of the movable contact member and pivotally connected thereto, a rotary eccentric cam for actuating the controlling member and said cam having its axis of rotation in alignment with the path of movement of the axis of the movable contact member whereby accelerated speed of the rolling movement occurs at the intermediate period thereof.

7. Switching apparatus of the character described comprising a stationary contact member, a movable contact member provided with a curved surface contact for rolling contact engagement with the stationary contact, a controlling member supported for movement in a plane coinciding with the axis of rotation of the movable contact member and pivotally connected thereto, a roller Journalled on the pivotal connection, a rotary excentric cam for actuating the controlling member, said cam having its axis of rotation in alignment with the path of movement of the axis of rotation of the movable contact member and a spring supported for engagement with the controlling member at the side opposite to the roller engagement with the cam.

8. Switching apparatus comprising a movable contact means periodically rolled to and fro, a stationary contact member periodically touched by said movable contact member, actuating means for the movable contact member consisting of two synchronously rotated cam discs having equal angular positions, a control member pivotally connected to the movable contact member and having an idler engaged by the cam discs, said cam discs having the axis of rotation positioned in alignment with the path of movement of the roller and a guide rail engaged by the roller and extending in a plane parallel to a straight line passing through the centers of rotation of the cam discs.

9. Switching apparatus of the character described comprising a stationary contact member, a movable contact member provided with a curved surface contact for rolling contact engagement with the stationary contact, a roller pivotally supported on the movable contact member at its axis of rotation and actuating means therefor comprising a rotatable eccentric provided with a groove receiving the roller and said eccentric having its axis of rotation in alignment with the path of movement of the movable contact member axis thereby to eifect accelerated speed at the intermediate period of the contact REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,537,466 Hunter May 12, 1925 1,057,219 Lehman Feb. 25, 1913 1,459,678 Lee June 19, 1923 1,732,694 Pescara Oct, 22, 1929 841,106 Bijur Jan, 15, 1907 

